A rocket fizzes through the air, crashing into the fourth-floor balcony above before exploding in a ball of sparks. People duck for cover.

There's a boom from a nearby alley as another detonation rings out. The dark sky above us is streaked with starbursts of fluorescent light.

You're not supposed to mention the war in Germany, so this could get delicate. The Fawlty Towers rule is one I'll probably break quite soon.

Berlin seems to be sending out a challenge to writers tonight, daring them to come up with a description that avoids mention of combat.

I'm racking my brains - a violent theme park? A closing ceremony for anarchists? A twisted celebration of sound and light? None of that does it justice. So here goes: Berlin, right now, is like a war zone.

It's nuts. There's rubbish littering the streets. There are people darting onto the road to set up rockets in empty beer bottles, lighting their fuses before running for cover.

Whoosh! The spark hits the rocket and it shoots high into the air, eventually exploding in a ball of light.

There's a feeling of lawlessness tonight, as if anything could happen. Anything already has happened.

As the clock struck midnight the whole of Berlin seemed to explode, the glow of light from the official firework display at Brandenburg Gate dwarfed by the unofficial firework displays that erupted from the city's every roof.

It's now New Year's Day, 2013, but it feels like the apocalypse.

This whole thing began a week ago, when the corner stores started hanging out their signs advertising "Feuerwerk" and the city's residents started stocking up. Soon, the explosions began.

At first there would be only one every now and then, a "boom!" as you wandered down a back street of Kreuzberg, or a sharp crackle from a park in Prenzlauer-Berg.

But as New Year's Eve grew closer they started to become more frequent, until it became obvious that Berlin was going to explode.

This will be a memorable NYE, we were thinking, not one of the usual ones - for reasons right and wrong.

It was T-minus four hours until midnight when my friend Kelly and I stepped out onto the streets of Berlin and the place was already rocking, with explosions popping like drum beats.

Kids were walking around with these bundles of sticks, each one tipped with a gaudily coloured rocket.

They set them off in the street, hoping the trajectory was right so it would soar into the sky and explode, rather than careen left or right towards someone's apartment.

A few took that detour, crashing into walls and exploding in clouds of sparks.

Kelly and I had been invited to a house party on a rooftop in the central suburb of Mitte, so we headed up there to take in the scene from the top.

Like many European cities Berlin has a low, flat skyline, interrupted only occasionally by large towers. From the roof we could see across the whole city, and it was on fire. Rockets appeared in full 360; you didn't know where to look.

This was merely a prequel, however; when the countdown eventually reached zero the whole city erupted, the sky more light than dark as rockets whistled and crackled, criss-crossing above in a hail of fire.

I got to light one. I was handed a cigarette lighter and ushered towards the rockets, told to pick one and set it up in a beer bottle.

I felt like - here we go again - a soldier setting a mortar as I lit the fuse and darted back into the group, watching with ridiculous pride as my rocket soared into the night and exploded on cue. Woo hoo!

But now, late in the evening, early in the apocalyptic morning, things have progressed. We've left the party and are back on the Mitte street, where anarchy reigns supreme.

There are people everywhere, running to light rockets, running to avoid them, setting off little crackers and big boomers, swigging from beer bottles and laughing and staggering in the night.

We head to the suburb of Kreuzberg to continue the party, dancing until dawn and then continuing on, flinching at each explosion, laughing at our fear.

Finally, about 10am, it's time to go home and we stumble in the strengthening light through Berlin's streets, taking in the destruction of a grand celebration.

There's litter everywhere, strewn among graffitied walls. Shell-shocked people like us wander through it in a daze, trying not to think about the clean-up. This city just hosted a night we'll never forget. But right now... it looks like a bomb hit it.